A plant is one type of light sensitive object that can be grown in a controlled light environment. Growing plants under controlled conditions such as in greenhouses, growth cabinets or warehouses, generally entails monitoring the plant environment and controlling parameters such as light, water vapor pressure, temperature, CO2 partial pressure, and air movement, in order to adjust the microclimate of the environment for optimizing growth and photosynthesis in an empirical manner. Plant attributes such as quantitative morphological, physiological and biochemical characteristics of at least a part of the plant may also be modulated during the monitoring of the plant environment and controlling of environment parameters.
Having the ability to determine the physiological condition of a plant or a group of plants is useful in implementing photosynthetic responses into climate control algorithms or models that can be used in a controlled light environment. Optimization of photosynthesis of crops or plant material can be achieved through careful and planned manipulations of growth conditions based on in-situ monitoring of relevant photosynthetic processes. Relevant and short-term plant responses are involved in the definition of growth requirements not only through climate control, but also through the production processes, fertilizers, light quality, light intensity, and crop quality.
To effectively control the climate, irrigation, nutrition and light regime of greenhouse crops in order to beneficially modulate and control growth and attributes of crops, sensors as well as models can be incorporated into a feed-forward/feedback component of a lighting system. Feed-forward controllers can use lamp light output to provide the necessary input for plant growth and have the capacity to anticipate the effects of disturbances on the greenhouse climate and in the light environment and take action within precisely set limits. Specific crop models, developed for individual crop species, can be based on data from sensors and used to estimate the benefits of changing growth regimes (e.g., spectral quality of the light source) to influence or modulate the outcome (e.g., flowering time). To this extent, the data obtained by the sensors can be combined with model-based algorithms in a lighting system to direct specific changes that influence the plant's growth processes or attributes.